WebGPURenderer: Fix global references in Node.js (#29919)

* Fix compilation in react

* Cleanup fixes

* Fix space

* Fix space

* Update WebGPUBackend.js

Use `null` as fallback when navigator isn't available.

* Update WebGPUUtils.js

Revert.

---------

Co-authored-by: Michael Herzog <michael.herzog@human-interactive.org>

src/renderers/webgpu/WebGPUBackend.js

@@ -64,7 +64,7 @@ class WebGPUBackend extends Backend {
 				powerPreference: parameters.powerPreference
 			};
 
-			const adapter = await navigator.gpu.requestAdapter( adapterOptions );
+			const adapter = ( typeof navigator !== 'undefined' ) ? await navigator.gpu.requestAdapter( adapterOptions ) : null;
 
 			if ( adapter === null ) {
 

src/renderers/webgpu/nodes/WGSLNodeBuilder.js

@@ -19,7 +19,7 @@ import ExpressionNode from '../../../nodes/code/ExpressionNode.js';
 import { NoColorSpace, FloatType, RepeatWrapping, ClampToEdgeWrapping, MirroredRepeatWrapping, NearestFilter } from '../../../constants.js';
 
 // GPUShaderStage is not defined in browsers not supporting WebGPU
-const GPUShaderStage = self.GPUShaderStage;
+const GPUShaderStage = ( typeof self !== 'undefined' ) ? self.GPUShaderStage : { VERTEX: 1, FRAGMENT: 2, COMPUTE: 4 };
 
 const accessNames = {
 	[ NodeAccess.READ_ONLY ]: 'read',
@@ -133,7 +133,7 @@ const wgslMethods = {
 
 // WebGPU issue: does not support pow() with negative base on Windows
 
-if ( /Windows/g.test( navigator.userAgent ) ) {
+if ( typeof navigator !== 'undefined' && /Windows/g.test( navigator.userAgent ) ) {
 
 	wgslPolyfill.pow_float = new CodeNode( 'fn tsl_pow_float( a : f32, b : f32 ) -> f32 { return select( -pow( -a, b ), pow( a, b ), a > 0.0 ); }' );
 	wgslPolyfill.pow_vec2 = new CodeNode( 'fn tsl_pow_vec2( a : vec2f, b : vec2f ) -> vec2f { return vec2f( tsl_pow_float( a.x, b.x ), tsl_pow_float( a.y, b.y ) ); }', [ wgslPolyfill.pow_float ] );
@@ -151,7 +151,7 @@ if ( /Windows/g.test( navigator.userAgent ) ) {
 
 let diagnostics = '';
 
-if ( /Firefox|Deno/g.test( navigator.userAgent ) !== true ) {
+if ( ( typeof navigator !== 'undefined' && /Firefox|Deno/g.test( navigator.userAgent ) ) !== true ) {
 
 	diagnostics += 'diagnostic( off, derivative_uniformity );\n';